132
FXUS65 KBOI 151039
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
339 AM MST SUN DEC 15 2024
SHORT TERM...TODAY THROUGH TUESDAY NIGHT
SHOWERS ACROSS
SOUTHWEST IDAHO ARE EXPECTED TO TAPER OFF BY 6 AM AS AN UPPER-
LEVEL TROUGH EXITS THE REGION. FOLLOWING THIS, COOLER AND DRIER
CONDITIONS WILL PREVAIL FOR THE REST OF THE DAY AHEAD OF THE
NEXT WEATHER SYSTEM ARRIVING ON MONDAY. WINDS WILL INCREASE
AHEAD OF AN APPROACHING WARM FRONT, SUPPORTING ABOVE- NORMAL
TEMPERATURES TODAY.
THE NEXT STORM SYSTEM REMAINS ON TRACK TO BRING ANOTHER ROUND
OF PRECIPITATION TO THE AREA STARTING LATE TONIGHT WITH A WARM
FRONTAL PASSAGE MOVING FROM SOUTHWEST TO NORTHEAST. INITIALLY,
LIGHT SNOWFALL WILL PRIMARILY AFFECT SOUTHEAST OREGON, THE LOWER
SNAKE PLAIN/WEISER BASIN, AND THE WEST-CENTRAL IDAHO MOUNTAINS.
MEANWHILE, SOUTHWEST WINDS ALOFT WILL CREATE A SHADOW EFFECT,
LIMITING PRECIPITATION FOR PARTS OF THE SNAKE PLAIN, ESPECIALLY
FROM BOISE EASTWARD.
PRECIPITATION WILL SPREAD EASTWARD MONDAY AFTERNOON, TRACKING
WITH THE UPPER LOW AS IT MOVES INTO SOUTHEAST OREGON. SNOW
LEVELS LOOK TO STAY LOW ENOUGH ACROSS SOUTHEAST OREGON AND THE
WEISER BASIN TO PRODUCE MODERATE ACCUMULATIONS, POTENTIALLY
REACHING VALLEY FLOORS. THIS COULD IMPACT THE MONDAY MORNING
COMMUTE, PARTICULARLY FROM BAKER CITY THROUGH ONTARIO, WHERE
THERE IS A 60% CHANCE OF AT LEAST HALF AN INCH OF SNOW. THE
REMAINING VALLEY AREAS (CALDWELL THROUGH BOISE AND INTO THE
WESTERN MAGIC VALLEY), GUIDANCE SUGGESTS ABOUT A 50% CHANCE OF
MEASURABLE SNOWFALL, THOUGH THE LIKELIHOOD OF AN INCH OR MORE IS
LESS THAN 5% THROUGH MONDAY AFTERNOON. IN THE MOUNTAINS,
WIDESPREAD MODERATE SNOWFALL IS EXPECTED, WITH TOTALS RANGING
FROM 5 TO 10 INCHES POSSIBLE BETWEEN MONDAY AND TUESDAY.
BY TUESDAY, ENSEMBLE MODELS INDICATE A RIDGE BUILDING ALONG THE
WEST COAST, SHIFTING THE STORM TRACK NORTHWARD ALONG WITH THE
PREVIOUSLY SHOWN WEAK SHORTWAVE. AS A RESULT, SNOW WILL LIKELY
CONTINUE IN THE CENTRAL IDAHO MOUNTAINS AND BAKER COUNTY, WHILE
OTHER AREAS WILL SEE LITTLE TO NO ADDITIONAL PRECIPITATION. THIS
SETUP FAVORS A RETURN TO ANOTHER VALLEY INVERSION, BRINGING
STRATUS CLOUDS AND FOG TUESDAY NIGHT.
LONG TERM...WEDNESDAY THROUGH SUNDAY
A WEEK RIDGE WILL
DEVELOP WEDNESDAY, WITH MOSTLY DRY CONDITIONS EXPECTED. THE
EXCEPTION WILL BE OVER NORTHEAST OR AND W-CENTRAL ID, WHERE A
QUICK-MOVING TROUGH WILL SKIRT NORTHEAST OREGON AND WEST-CENTRAL
IDAHO AND BRING A 20-30 PERCENT CHANCE OF SHOWERS FOR THOSE
LOCATIONS WEDNESDAY. THEREAFTER, THE UPPER LEVEL RIDGE IS
EXPECTED TO AMPLIFY OVER THE INTERMOUNTAIN WEST WEDNESDAY
THROUGH EARLY SATURDAY, SUPPORTING THE FORMATION OF COLD POOLS,
PATCHY FOG, AND STAGNANT CONDITIONS FOR THE VALLEYS WHILE
MOUNTAINS TREND WARMER. LATEST MODEL RUNS HAVE A WEAK, MOSTLY
DRY TROUGH ARRIVING LATE SATURDAY, THEN A STRONGER TROUGH
ARRIVING SUN/MON. THIS STRONGER TROUGH WILL BRING A RELATIVELY
HIGH PROBABILITY (50-70 PERCENT) OF PRECIPITATION ACROSS THE
REGION, ALONG WITH ENOUGH WINDS TO DISTURB THE VALLEY
INVERSIONS.
AVIATION
CONDITIONS IMPROVING TO VFR AT MOST TAF SITES AS
RAIN/SNOW ENDS THIS MORNING. CONTINUING IFR/LIFR AND MTN OBSCURATION
IN SNOW SHOWERS FOR NORTHEAST OR AND W-CENTRAL ID THROUGH THIS
AFTERNOON. AFTER MON/06Z, PRECIPITATION SPREADING FROM W TO E
PROMOTING MVFR TO LIFR CONDITIONS. SNOW LEVELS AT VALLEY FLOORS,
RISING IN THE AFTERNOON. SURFACE WINDS: SW-NW 5-15 KT. AT KJER/KTWF,
SW-W 15-25 KT GUSTS TO 25-35 KT DECREASING TO 10-15 KT WITH GUSTS UP
TO 20-25 KT THIS AFTERNOON. WINDS ALOFT AT 10KFT MSL: W-NW 20-35 KT.
KBOI...VFR TODAY. A 30% CHANCE OF SNOW OR RAIN/SNOW MIX ARRIVING
EARLY MONDAY, THEN ALL RAIN MONDAY AFTERNOON. LOW VFR/MVFR IN
PRECIPITATION. LIGHT SNOW ACCUMULATIONS POSSIBLE EARLY MON. SURFACE
WINDS: NW 5-10 KT, BECOMING SE 5-10 KT AFTER SUNSET.
BOI WATCHES/WARNINGS/ADVISORIES
ID...WINTER WEATHER ADVISORY UNTIL 5 AM MST EARLY THIS MORNING
IDZ011-013-028.
OR...NONE.
WWW.WEATHER.GOV/BOISE
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSBOISE
WWW.TWITTER.COM/NWSBOISE
SHORT TERM...JDS
LONG TERM....SH
AVIATION.....SH
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